The present invention relates to medical devices. More particularly, the invention relates to a removable intravascular filter that can be removed from the vena cava of a patient through the patient's jugular or femoral vein.
Filtering devices that are percutaneously placed in the vena cava have been available for a number of years. A need for such filtering devices arises in trauma patients, orthopedic surgery patients, neurosurgery patients, or in patients having medical conditions requiring bed rest or non-movement. Patients having such medical conditions face an increased risk of thrombosis in the peripheral vasculature, wherein thrombi break away from the vessel wall, risking downstream embolism or embolization. For example, depending on the size, such thrombi pose a serious risk of pulmonary embolism wherein blood clots migrate from the peripheral vasculature through the heart and into the lungs.
Historically, vena cava filters were considered to be permanent implants and remained implanted in the patient for life. More recently, removable vena cava filters have been developed. These filters may be removed from the patient's vena cava after the condition or medical problem that required the device has passed.
The benefits of vena cava filters, and particularly removable vena cava filters, have been well established, but improvements may be made. For example, the vast majority of the removable vena cava filters currently on the market must be removed through the patient's jugular vein. In some instances, however, removal through the patient's femoral vein is preferable to removal through the jugular vein. For example, filters sometimes shift or become stuck in a patient's vena cava. The ability to retrieve such troublesome filters from a different access point can increase the likelihood that they will be removed successfully. In addition, jugular retrieval requires that a retrieval sheath be advanced through the patient's heart, which is contraindicated in some cases. Finally, scarring at the access point is less noticeable when retrieval is initiated through the femoral vein.
It has been a challenge to design a vena cava filter suitable for removal through a patient's femoral vein.